PREFACE TO SECOND EDITION 



The recent progress in bacteriological science has made it necessary 

 to make certain changes and additions in the present volume. The fol- 

 lowing chapters have been added. Chapter III, The Origin of Bacteria; 

 Chapter VII, Symbiology; Chapter IX, Zymology; and Chapter XII, 

 Adenology. In addition to this wholly new matter, not given in the first 

 edition, other additions have been made in the text. " The subject of soil 

 bacteriology and of milk and water analysis, has been treated more fully. 

 The chapter on sterilization and disinfection has been enlarged. A brief 

 statement of sensitized bacterins, of anaphylaxis, of aggressins and of 

 storing biologies has been introduced. Some of the disputed points 

 have been cleared up or have been entirely omitted. The many imper- 

 fections of a first edition of a book covering a new field of scientific en- 

 deavor, or to put it more correctly, a new application of a science, namely 

 ■ the science of bacteriology to pharmacy, have been largely corrected. 

 A text-book deals with the established facts of science, giving just 

 enough of the theoretical to indicate the further advance in the near or 

 perhaps remote future. The present volume has adhered to this require- 

 ment. It is possible to present the facts of science intelligently without 

 using difficult words or complicated phraseology. A suitable text must 

 not be encumbered by unnecessary technical terms, nor should it be a 

 mere glossary of scientific terms. If definitions were all that is required 

 of a text-book, then Webster's Unabridged Dictionary would be the ideal 

 universal text-book for all grades \and classes of students. It is believed 

 that the present volume is not faulty in these regards. It is believed that 

 the book will be found quite "readable" and intelligible to the 

 student of ordinary ability. 



Grateful acknowledgments are hereby made to Dr. Aubrey H. 

 Straus of the Medical College of Virginia, for many suggestions and for 

 calling attention to soi^e of the more glaring imperfections in the first 

 edition. The present volume is believed to be complete for the purpose 

 for which it is intended. 



Lincoln, Nebraska, 

 December, 191 9. 



